Cannabis has never killed anyone, but that hasn’t stopped American health experts from warning against the possible problems that the all-natural plant can cause. With California set to start recreational weed sales in five weeks, San Francisco health officials have released a comprehensive set of health concerns that they predict could arise from the state’s newly legal marijuana market, focusing on teen abuse and ensuring that "perceptions of cannabis recognize risks associated with use." But as California health experts continue to compare cannabis to alcohol in their approach to issues like driving under the influence and workplace use, one group of researchers wants cannabis health protocols to take a closer look at the similarities between marijuana and tobacco.

“The evidence that secondhand exposure to marijuana smoke, like the evidence for all health effects of marijuana, is more limited than for tobacco,” the study’s authors write. “But smoke from any source is a complex mixture of thousands of chemicals, including ultrafine particles and toxic gases. Other than nicotine and cannabinoids, tobacco and marijuana smoke are similar. Indeed, the California Environmental Protection Agency identified marijuana smoke as a human carcinogen based largely on the smoke’s toxicology.”

The study goes on to argue that if the 4/20 party were a public cigarette smoking celebration, it would have been “unthinkable (and illegal).”

“In contrast to tobacco, marijuana is widely viewed as harmless or even good for you, even something to be celebrated,” the study’s authors added.

However, according to the San Francisco Chronicle, it appears that the city by the bay is putting secondhand smoke on the backburner for now, focusing on other legal weed issues such as keeping the plant away from children, the often unpredictable effects of edibles, and the possible problems caused by addiction and intoxication. On the topic of smoke inhalation, experts have largely focused on personal use, remaining silent on the topic of secondhand exposure.

“The work we’ve done has said you want to avoid smoke. That would mean you steer people toward edibles,” said Springer, who studies the effects of tobacco and marijuana smoke on the heart at University of California San Francisco, to the Chronicle. “But personally, I know someone who tried taking (cannabis) capsules and ended up going to ER with paranoia and palpitations. There are health effects from both approaches to taking this drug and trying to roll that into a health policy becomes complicated.”

And while public health regulations surrounding legal weed will continue to evolve with the implementation and growth of recreational cannabis sales, the JAMA study authors are hopeful that the agreed upon dangers of smoke inhalation (first and secondhand; no matter the substance burned) will at least stop public consumption locations from opening in California and other legal weed states.

“This evidence supports maintaining and expanding clean indoor air laws to include marijuana as part of a public health framework for marijuana regulation,” the study concludes. “Stressing the right of all to breathe clean air should also be at the core of educational and legislative efforts to reinforce the marijuana smoke-free norm for everyone.”

But with San Francisco only months away from the city’s first 4/20 celebration with fully legal adult-use cannabis, we’re guessing few will heed the recent study’s warning, and Golden Gate Park will once again be home to tens of thousands of smokers, no matter how many carcinogens they, or others, are inhaling.